Jülich researchers present new insights into the climate impact of contrails and climate-optimized flight routes at an international climate conference
8 June 2026
How can aviation effectively reduce its climate impact while simultaneously achieving the goal of climate-neutral air transport by 2050? This question was the focus of the second ICAO Aviation Climate Week, which took place from June 2 to 4 at the headquarters of the United Nations International Civil Aviation Organization (ICAO) in Montreal.
In a high-level opening discussion, Andreas Petzold from Forschungszentrum Jülich, together with Marc Stettler from Imperial College London, presented the latest scientific findings on the climate impacts of aviation.
The discussion focused on the effects of so-called non-CO₂ emissions from aviation—and in particular contrails—on the climate, as well as ways to reduce aviation’s climate impact. Neil Dickson, Head of the Environmental Standards Section at ICAO and moderator of the event, explicitly highlighted the importance of the international research program IAGOS (In-service Aircraft for a Global Observing System), which is co-coordinated by Forschungszentrum Jülich.
Indeed, a lot of what we know today on the regions where contrails form is thanks to the IAGOS programme.
Marc Stettler discussed the opportunities and challenges of current international strategies to avoid contrails with particularly significant climate impacts. Andreas Petzold presented findings from a highly acclaimed Jülich study showing that long-lived contrails often form in natural ice clouds and that their actual climate impact is not yet sufficiently understood.
“We must significantly improve weather forecasting through a close coalition of ICAO, weather services, the aviation industry, and research so that commercial aircraft can use climate-friendly flight routes on their way to their destination,” said Petzold. “To do this, we need to take clouds into greater account during flight planning.”
The discussion made it clear that, in addition to reducing CO₂ emissions, the so-called non-CO₂ effects of aviation must also be given greater consideration in the future. Scientific findings from programs such as IAGOS provide an important basis for this. They help to better identify regions with increased contrail potential and to develop climate-optimized flight routes in the future.
Through its participation in ICAO Aviation Climate Week, Forschungszentrum Jülich underscores its role as an internationally recognized partner in atmospheric and climate research, as well as in the development of scientific foundations for more sustainable aviation.
IAGOS – Climate Research from Cruise Altitude
IAGOS (In-service Aircraft for a Global Observing System) is one of the “Landmark Research Infrastructures” of the European Strategy Forum on Research Infrastructures (ESFRI). The project has been operating since 1994 with long-term support from the German Federal Ministry of Education and Research (BMFTR).
Measuring instruments on board commercial aircraft record key atmospheric parameters worldwide at cruising altitude. These include long-lived carbon dioxide (CO₂), short-lived greenhouse gases such as ozone, water vapor, and methane, the reactive trace gases carbon monoxide and nitrogen oxides, as well as aerosol particles. Within IAGOS, the Jülich atmosphere researchers at the institute of climate and energy systems (ICE-3) are responsible for the measurement systems for water vapor, nitrogen oxides, and aerosol particles.
After each flight, the data is automatically transmitted to the central database of the French research center CNRS (Centre National de la Recherche Scientifique) in Toulouse. The measurement data is freely available to the international scientific community and is currently used by around 300 organizations worldwide.
The data helps to better understand the composition of the atmosphere and climate change, document long-term changes, improve climate models, and make weather forecasts more accurate.
Currently, ten commercial aircraft from eight international airlines are equipped with the IAGOS measurement system.
Contribution to climate-friendly aviation: The data collected by IAGOS provides an important scientific basis for better predicting the formation of climate-impacting contrails and for developing climate-optimized flight routes in the future.
ICAO Aviation Climate Week 2026
